Various attempts have been made to control weeds and other unwanted growth which occurs in furrows between the dikes used for the growing of vegetables and fruits. These dikes usually are covered in plastic to limit the amount of unwanted growth on the dikes. The crops at the top of the dikes pass through slits in the plastic. The furrows between adjacent dikes are used for irrigation purposes and travel of farm equipment. Unwanted weeds grow in the furrows which compete with the food product for the nutrients and water contained in the soil.
In U.S. Pat. No. 3,581,993 to Reams, a foldable agricultural spray boom incorporates a hydraulic cylinder which causes the boom to unfold when actuated by the pressurized spray liquid. In the unfolded position, a valve establishes a fluid path through the cylinder to the boom spray nozzles.
U.S. Pat. No. 1,462,861 to Jordan and U.S. Pat. No. 4,353,505 to Kinder disclose crop sprayers with skirts to limit the spray or dust to a row of planted crops. The Kinder patent also discloses a drift-free spray apparatus adapted for movement in connection with a vehicle and includes a spray bar mounted within a bottomless, rectangular, box-type housing in communication with a fluid pump and reservoir assembly, adapted for emitting fluid in a mist configuration upon the surface to be sprayed through nozzles provided in the spray bar.
U.S. Pat. No. 3,445,961 to Elsworth, U.S. Pat. No. 3,977,605 to Sheldon, U.S. Pat. No. 4,350,294 to Gaspard, and U.S. Pat. No. 4,736,888 to Fasnacht discloses herbicide sprayers for use in planted fields. These patents include various means for protecting the crops, either by carefully limiting the spread of the herbicide spray or by shielding the crops from the spray. In the Gaspard patent, spray nozzles are disclosed as being mounted on pivoting arms including a skid which runs along a furrow. This keeps the nozzle at a constant height and allows control of the spread of the herbicide without lateral control.
In my prior patent, U.S. Pat. No. 5,248,090, herein incorporated in its entirety by reference, a plurality of spray chambers are mounted on a boom secured to a three-point trailer hitch of a tractor. Controlled herbicide spraying of the unwanted growth which occurs in the furrows between dikes in fields of strawberries, lettuce, corn, tomatoes, onions, and other crops is achieved. Each spray chamber includes two overlapping sections which are movable towards and away from each other against the bias of springs so that varying widths of furrows between adjacent dikes are accommodated. In addition, an entire spray chamber is laterally adjustable to accommodate varying distances between adjacent furrows as is encountered due to "blow outs" of dikes due to over-watering or storm conditions to cause partial collapse of a dike.
An attempt is made in the '090 patent to limit the spray of herbicide to vegetation located in the furrow between dikes so as to eliminate any accidental spraying of the adjacent crops located on top of the dikes. This would avoid the drift of herbicide during high wind conditions which could accidentally kill the crops, and therefore spraying may occur at any time, avoiding the necessity to wait for good weather for herbicide spraying.
The boom onto which the plurality of spray chambers are mounted includes lift cylinders to elevate sections of the boom for higher speed travel when not spraying. Each of the spray chambers includes a chain link connection to the boom at the rear of the spray chamber to limit the extent of drop of the spray chambers when lifting the boom sections. In addition, each spray chamber includes a slidable connection to the boom at the front of each spray chamber for a lateral adjustment of the spray chambers. The chain link connection also prevents excessive drop cf the rear of the spray chambers when passing over a ditch caused by over-watering of the field, or other adverse conditions.
The lateral and height positioning of spray nozzles within each spray chamber are adjustable. By these adjustments, an attempt is made to have accurate herbicide spraying of the furrows of a field.